The purpose of this application is to request partial support of symposia to be held in connection with the 18th Annual National Meeting of the Reticuloendothelial Society (RES). The Grantee shall organize and conduct the symposia, which are to be held at the Hotel Pfister, Milwaukee, Wisconsin, on 12-16 October 1981. A relatively small Society such as the Reticuloendothelial Society, about l000 members, plays an important part in specific communication, which is the major function of the Annual Meeting. The Society has considerable impact in the macrophage and cancer fields and attracts top quality scientists as members, representing a variety of disciplines in the biomedical sciences.